Steerable catheter with brake assembly

ABSTRACT

A catheter includes a handle and an elongate member extending from the handle. The catheter may also include steering system coupled to the handle. The steering system may be configured to deflect at least a portion of the elongate member in at least one direction. The catheter may also include a locking mechanism configured to lock the portion of the elongate member in a deflected configuration, and a lever coupled to the handle. The lever may be configured to move from a first position to a second position to engage the locking mechanism. The lever may also be configured to be separably retained at least at one of the first position or the second position to prevent movement therebetween.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority from U.S. ProvisionalApplication No. 61/706,307, filed Sep. 27, 2012, the entirety of whichis incorporated by reference herein.

BACKGROUND OF THE INVENTION

Minimally invasive surgical tools, such as endoscopic and laparoscopicdevices, provide access to areas or work sites within a mammalian bodywhile minimizing patient trauma. These devices allow physicians toperform a variety of diagnostic and therapeutic tasks at a desired worksite within the body by controlling the device from outside the body. Inan exemplary procedure using such a device, the device is inserted intothe body through a natural orifice or an incision, and positioned withits distal end proximate the work site. Surgical or diagnostic tools maythen be delivered to the work site through the inserted device andcontrolled from outside the body to perform the desired task. While thistask is performed, care must taken to prevent inadvertent movement ofthe endoscopic device and its associated tools. The current disclosurerelates to an endoscopic device with a braking assembly to preventinadvertent movement of the device within the body.

SUMMARY OF THE INVENTION

In one embodiment, a catheter is disclosed. The catheter may include ahandle and an elongate member extending from the handle. The cathetermay also include steering system coupled to the handle. The steeringsystem may be configured to deflect at least a portion of the elongatemember in at least one direction. The catheter may also include alocking mechanism configured to lock the portion of the elongate memberin a deflected configuration, and a lever coupled to the handle. Thelever may be configured to move from a first position to a secondposition to engage the locking mechanism. The lever may also beconfigured to be separably retained at least at one of the firstposition or the second position to prevent movement therebetween.

Various embodiments of the invention may also include one or more of thefollowing aspects: the locking mechanism may include a rack gear and atleast one pinion gear that mate when the locking mechanism is engaged bythe lever; the steering system may include at least one spool that isconfigured to rotate to deflect the portion of the elongate member, theat least one pinion gear may be coupled to the at least one spool suchthat relative rotation between them is prevented; movement of the leverfrom the first position to the second position may cause the rack gearto mate with the at least one pinion gear; the steering system mayinclude two spools, each spool may be configured to deflect the portionof the elongate member in a different direction, wherein the rack gearprevents the rotation of both spools when the locking mechanism isengaged by the lever; the locking mechanism may include a cam thatrotates to push the rack gear towards the at least one pinion gear whenthe lever moves from the first position to the second position; thelocking mechanism may include a leaf spring configured to act as aninterface between the cam and the rack gear; the locking mechanism mayinclude a spring configured to bias the rack gear in a direction awayfrom the at least one pinion gear; the locking mechanism may include aspring configured to bias the lever towards the handle, and the handlemay include a retention feature configured to retain the lever at leastat one of the first position or the second position; the retentionfeature may be an opening in the handle, and the lever may be separablyretained by the handle by accommodating a distal end of the lever in theopening; and the lever may be configured to be pulled in a directionaway from the handle and pivot relative to the handle to move from thefirst position to the second position.

In another embodiment, a catheter is disclosed. The catheter may includea handle, an elongate member extending from the handle, and a steeringsystem with a locking mechanism. The steering system may include atleast one spool configured to rotate to deflect at least a portion ofthe elongate member in at least one direction, a pinion gear fixedlycoupled to the at least spool, and a rack gear configured to engage withthe pinion gear to lock the portion of the elongate member in adeflected configuration.

Various embodiments of the invention may also include one or more of thefollowing aspects: the steering system may include a cam configured topush the rack gear towards the pinion gear; the steering system mayinclude a lever coupled to the handle and configured to move from afirst position to a second position to engage the rack gear with thepinion gear; the lever may include a releasable lock that is configuredto prevent movement of the lever between the first position and thesecond position; the releasable lock may include a spring that biasesthe lever towards a retention feature on the handle; and the steeringsystem may include two spools, each spool may be fixedly coupled to apinion gear, wherein each spool is configured to deflect the portion ofthe elongate member in a different direction.

In another embodiment, a method of using a catheter including a handlewith an elongate member extending therefrom, is disclosed. The methodmay include positioning the catheter in a body with a distal end of theelongate member within the body and the handle outside the body, andactivating a steering mechanism to deflect at least a portion of theelongate member in at least one direction. The method may also includeengaging a locking mechanism of the catheter to lock the portion of theelongate member in a deflected configuration. Engaging the lockingmechanism may include pulling a brake lever away from the handle torelease a lock of the lever, and moving the lever from a first positionto a second position.

Various embodiments of the invention may also include one or more of thefollowing aspects: moving the lever may include rotating a cam to push arack gear into engagement with a pinion gear fixedly coupled to a spoolof the catheter; and the method may further include disengaging thelocking mechanism by moving the lever from the second position to thefirst position.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate exemplary embodiments of theinvention and together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a perspective view of an exemplary steerable catheter of thecurrent disclosure.

FIG. 2 illustrates an exemplary articulation portion of the catheter ofFIG. 1 .

FIG. 3 illustrates inner portions of exemplary handle of the catheter ofFIG. 1 .

FIG. 4 illustrates a simplified cross-sectional view of portions of thehandle of FIG. 3 .

FIG. 5 illustrates an exemplary spool of the catheter of FIG. 1 .

FIGS. 6A and 6B illustrate portions of the steering system of thecatheter of FIG. 1 .

FIG. 7A illustrates an exemplary arrangement of a pinion and a spool ofthe catheter of FIG. 1 .

FIG. 7B illustrates an exemplary brake bracket of the catheter of FIG. 1.

FIG. 8 illustrates an exemplary method of using the steerable catheterof FIG. 1 .

DETAILED DESCRIPTION

Disclosed herein are systems and methods for performing a medical taskwithin a body by controlling devices and/or tools, inserted into thebody, from outside the body. Although the current disclosure isgenerally applicable to any type of device inserted into the body toperform a diagnostic or a therapeutic task (such as, for example,endoscope, laparoscope, arthroscope, bronchoscope, colonoscope,cystoscope, enteroscope, hysteroscope, laryngoscope, mediastinoscope,sigmoidoscope, thoracoscope, catheter, sheath, etc.), for the sake ofbrevity, the inserted device is referred to herein as a steerablecatheter. The catheter may be adapted for any type of access within thebody (such as, for example, trans-oral, trans-anal, trans-vaginal,trans-urethral, trans-nasal, transluminal, laparoscopic, thorascopic,orthopedic, through the ear, and/or percutaneous access), and may beconfigured to perform any type of task (diagnostic, therapeutic,surgical, etc.) within the body. It is to be understood that both theforegoing general description and the following detailed description areexemplary only and are not restrictive of the invention, as claimed.

FIG. 1 is a perspective view of an exemplary embodiment of a steerablecatheter 20 configured to perform a task within a mammalian body.Catheter 20 includes a handle 22 with an elongate member in the form ofan insertion shaft or a guide tube 24 extending therefrom. In use, adistal end 28 of the guide tube 24 is inserted into the body andmaneuvered to suitably position the distal end 28 proximate a work sitewithin the body. In this configuration, the handle 22 is positionedoutside the body with at least a portion of the guide tube 24 within thebody. The handle 22 and the guide tube 24 may be made of any suitablematerial. Typically, the guide tube 24 is made of a biocompatiblematerial such as, for example, nylon, polytetraflouroethylene (PTFE),polyethylene, thermoplastic elastomers, etc. Items, such as, forexample, surgical or therapeutic tools, angioplasty balloons, stents,baskets, fiber optic scopes, light source, camera, etc. may beintroduced to the work site within the body through the catheter 20. Forinstance, to introduce a surgical tool to the work site, the tool may beinserted into the catheter 20 through ports 40 a, 40 b on the handle 22,and pushed in to extend end effectors at the distal end of the tool outthe distal end 28 of the guide tube 24. Actuation devices at theproximal end of the tools may be used by an operator of the catheter 20(such as, for example, a surgeon) to manipulate the end effectors of thetools at the work site. In some embodiments, the catheter 20 mayinclude, or engage with, a frame or another support device to supportthe handle 22 on a fixed object, such as an operating table frame.

Guide tube 24 includes an elongate body 30 that extends from a proximalend 26 to the distal end 28. The proximal end 26 of the guide tube 24 iscoupled to the handle 22. The outer surface of elongate body 30 mayinclude a layer of lubricous material to facilitate insertion of theguide tube 24 into the body. The interior of elongate body 30 mayinclude one or more channels or lumens coupled to one or more of theports 40 a, 40 b, and adapted to guide the tools to the work site. Thenumber of lumens and their configuration may be varied depending on theintended use of the catheter 20 and the number and type of toolsrequired during a procedure.

Elongate body 30 of guide tube 24 includes a proximal portion 30 a, amid portion 30 c and a distal portion 30 b. One or more of theseportions may be flexible and configured to flex to allow the guide tube26 to pass through tortuous passages within the body. One or more ofthese portions 30 a, 30 b, 30 c may also include an articulation portion32 (shown, for example, near the distal portion 30 b in FIG. 1 )configured to flex or bend by a desired amount in a desired direction inresponse to actuation by the surgeon. The articulation portion 32 mayprovide the guide tube 24 with multiple degrees of freedom. Catheter 20includes a steering system 50 that may be activated by the surgeon tocontrol the flexure or deflection of the articulation portion 32 andnavigate the guide tube 24 through body lumens and/or point the distalend towards a desired work site. In some embodiments, the steeringsystem 50 may include controls that may move the articulation portion 32along different degrees of freedom. For example, in an exemplaryembodiment, the steering system 50 includes a first dial (or knob) 50 athat may be rotated to move the articulation portion 32 up and down, anda second dial 50 b that may be rotated to move the articulation portion32 left and right (or side to side). In some embodiments, the steeringsystem 50 may also include controls that are configured to rotate atleast a portion of the guide tube 24 about an axis of the guide tube 24.Although the guide tube 24 is described as being configured to deflector flex at articulation portion 32, this is only exemplary. In someembodiments, guide tube 24 may include multiple flexible sections (suchas, multiple articulation portions 32) arranged along the length ofelongate body 30. Some of these multiple articulation portions may beconfigured to flex independently in response to activation by thesurgeon. Activation of these multiple articulation portions 32 mayenable the guide tube 24 to bend in complex shapes (such as, forexample, s-shape) in one or more planes and/or about one or more axes.

FIG. 2 illustrates an exemplary articulation portion 32 of the guidetube 24. Articulation portion 32 includes segments 34 that are pivotablycoupled together to form articulation joints that permit the segments 34to move (such as, for example, at least partially rotate) with respectto each other. In some embodiments, the lumens of the guide tube 24extend towards the distal end 28 through the inside of the segments 34.As the articulation portion 32 bends, the guide tube 24 along with thelumens bends. In some embodiments, some of the lumens extend through theinside of the segments 34 while others extend outside the segments 34.In some embodiments, a flexible covering (not shown), such as, forexample, a mesh or a braid, may be provided over the articulationportion 32 to prevent the segments 34 from binding, pinching, and/ordamaging the guide tube 24. A variety of control mechanisms may be usedto manipulate the articulation portion 32 and flex the guide tube 24. Insome embodiments, the control mechanism may include strings, wires,cable, or strands 60 a, 60 b, 60 c, and 60 d attached to one or more ofthe segments 34 to cause the segments 34 to move with respect to eachother. When tensioned, these strands 60 a, 60 b, 60 c, and 60 d bend thearticulation portion 32 in different directions by moving or rotating aseries of segments 34. For example, in some embodiments, strands 60 aand 60 b may couple opposite sides of one or more segments 34 to thefirst dial 50 a of the steering system 50. Rotating the first dial 50 amay exert a pulling force or tension on one of the strands 60 a, 60 band cause the segments 34 to bend the distal end 28 of the guide tube 24up or down. The other strands 60 c and 60 d may similarly couple thesegments 34 to the second dial 50 b to bend the articulation portion 32to the left and right. Articulation portion 32 may also include otherfeatures (not shown), such as, for example, springs, etc. that mayassist in the deflection of guide tube 24. The articulation portion 32and the segments 34 may include any suitable material. In someembodiments, the strands 60 a, 60 b, 60 c, and 60 d may be made of anelastic material, such as, for example, stainless steel. In someembodiments, the strands 60 a, 60 b, 60 c, 60 d include bowden cableswith an outer sheath (made of a material such as PTFE) covering alubricated inner filament.

The handle 22 supports a portion of the steering system 50 that may beactivated to deflect the guide tube 24 at the articulation portion 32.With reference to FIG. 1 , handle 22 may include a body formed by twohalf sections 22 a, 22 b that may be joined together by any suitablemethod (such as, for example, using adhesives) to enclose a spacetherebetween. FIG. 3 is an illustration of an exemplary handle 22 with ahalf section 22 a removed to show the structure within. Strands 60 a, 60b, 60 c, 60 d that are coupled to articulation segments 34 may extendfrom the articulation portion 32 to the handle 22 through the guide tube24. In some embodiments, these strands 60 a, 60 b, 60 c, 60 d may extendto the handle 22 through a lumen of the guide tube 24 and exit the lumeninto the handle 22. In some embodiments, the strands may enter thehandle 22 through a seal to prevent biological fluids from entering thehandle 22. Within the handle 22, the strands 60 a, 60 b, 60 c, 60 d arecoupled with the steering system 50 through a tensioner 36. Inembodiments where the strands are bowden cables, the outer sheath of thebowden cables terminate at the tensioner 36, while the inner filamentextends to the steering system 50. Tensioner 36 includes a spring 38that keeps the filament taut between the tensioner 36 and the steeringsystem 50, while allowing the portion of the cables distal to thetensioner 36 to flex and/or translate longitudinally.

The strands 60 a, 60 b, 60 c, 60 d may be coupled to spools (first spool52 a and second spool 52 b) of the steering system 50 that are connectedto the first and second dials 50 a, 50 b. In some embodiments, two ofthe strands may be coupled to a first spool 52 a and the other twostrands may be coupled to a second spool 52 b. For example, strands 60 aand 60 b may be coupled to opposite sides of the first spool 52 a, andstrands 60 c and 60 d may be coupled to the opposite sides of the secondspool 52 b. FIG. 4 illustrates a simplified cross-sectional view ofportions of the exemplary handle 22 of FIG. 3 to illustrate thefunctioning of the steering system 50. In the description that follows,reference will be made to both FIGS. 3 and 4 . The first spool 52 a maybe connected to the first dial 50 a such that rotation of the first dial50 a rotates the first spool 52 a and applies a pulling force to one ofthe strands 60 a, 60 b. As described previously, this pulling forcecauses the distal end 28 of the guide tube 24 to translate up or down atthe articulation portion 32. Similarly, the second spool 52 b may beconnected to the second dial 50 b such that rotation of the second dial50 b applies a pulling force on one of strands 60 c and 60 d and causesthe guide tube 24 to move left or right. It should be noted that thenumber and configuration of strands and spools is only exemplary. Theuse of two spools and four strands allows independent articulation ofthe guide tube 24 in the left-right direction and the up-down direction.One skilled in the art will appreciate that the steering system 50 mayalternatively be configured to control the up-down and left-rightdegrees of freedom of guide tube 24 in a different manner. In general,the number of strands and spools may depend on the number of degrees offreedom a catheter 20 is configured for. For example, in embodimentswhere the guide tube 24 is configured only to bend in one plane (forexample, left and right), steering system 50 may include only a singlespool and two strands.

The strands 60 a, 60 b, 60 c, 60 d may be coupled to the spools 52 a, 52b by any method. For example, in some embodiments, a strand may befixedly attached to a spool by welding, adhering, etc. While in otherembodiments, an end of a strand may be mechanically interlocked to aspool. FIG. 5 illustrates an exemplary embodiment of the spools (firstspool 52 a and second spool 52 b) in which strands 60 a and 60 b aremechanically interlocked with the first spool 52 a using retention tubes54 a, 54 b. In some embodiments, a terminal at the end of a strand (forexample, strand 60 a) may pass through a slot of a retention tube (forexample, retention tube 54 a) to mechanically interlock the strand withthe spool. The retention tubes 54 a, 54 b may be tangential pockets orother features machined into the first spool 52 a or may be a separatecomponent attached to the first spool 52 a. In some embodiments, theretention tubes 54 a, 54 b may be comprised of an annealed stainlesssteel or another material to allow for controlled deformation of thetubes while prophylactically preventing damage to the strands.

Steering system 50 may also include a brake mechanism 70 configured tolock the guide tube 24 in position once a desired configuration ofarticulation portion 32 is reached (see FIGS. 3 and 4 ). When engaged,the brake mechanism 70 provides a positive lock for the guide tube 24(and particularly the articulation portion 32) and prevents inadvertentmovement of the guide tube 24. FIGS. 6A and 6B illustrate portions ofthe steering system 50 showing an exemplary brake mechanism 70 ofcatheter 20. With reference to FIGS. 3, 4, 6A and 6B, in one embodiment,the brake mechanism 70 includes a rack gear or a shoe 72 and piniongears or pinions (first pinion 74 a and second pinion 74 b). Firstpinion 74 a may be coupled with the first spool 52 a such that relativemovement (or relative rotation) between the first spool 52 a and thefirst pinion 74 a is prevented. That is, the first spool 52 a and thefirst pinion 74 a may be fixedly coupled together and rotate as onepart. Similarly, the second pinion 74 b and the second spool 52 b may becoupled together such that relative movement between them is prevented.In some embodiments, a geometry of a pinion (for example, first pinion74 a) and a spool (for example, first spool 52 a) may ensure thatrelative movement between the pinion and the spool is prevented. FIG. 7Aillustrates an exemplary geometry of first pinion 74 a and first spool52 a that may be applied in brake mechanism 70. As illustrated in FIG.7A, the first spool 52 a may include a spindle with a flat region on itscircumference that may mate with a corresponding region of the firstpinion 74 a to prevent relative movement between them. It should benoted that the configuration illustrated in FIG. 7A is only exemplary,and relative movement between a pinion and a spool may be prevented byany method. For example, in some embodiments, a corresponding pinion anda spool may be attached using adhesives. It is also contemplated that insome embodiments, a corresponding pinion and a spool may be fabricatedas one part.

Engagement of the brake mechanism 70 forces the shoe 72 to mate with thefirst and second pinions 74 a and 74 b and prevent the rotation of thespools 52 a, 52 b. In some embodiments, the shoe 72 may be spring loadedsuch that the shoe 72 separates from the first and second pinions 74 aand 74 b and returns to a neutral position when the brake mechanism 70is disengaged. In some embodiments, the shoe 72 may be spring loaded bya torsion spring 76 (see FIGS. 6A, 6B) that biases the shoe in adirection away from the pinions. In some embodiments, shoe 72 may bestraight (as shown in FIGS. 6A and 6B), curved, or other shapes. It iscontemplated that in certain embodiments, engagement of a single toothof shoe 72 and first or second pinions 74 a and 74 b is sufficient tolock first and second spools 52 a and 52 b. It is also contemplated gearteeth may extend along the full length of shoe 72 or may extend along apartial length of shoe 72. For example, shoe 72 may have teeth that onlyextend along the portion or portions of shoe 72 that are configured toengage pinions 74 a and 74 b.

With reference to FIGS. 6A and 6B, the brake mechanism 70 may be engagedby pulling a spring loaded brake lever 80 upwards in the direction ofarrow B and rotating the brake lever 80 from a first position to asecond position in the direction of arrow A. The brake lever 80 may bebiased towards the handle 22 (that is, in a direction opposite arrow B)by a spring or by another mechanism. The handle 22 may lock into a slotin the handle 22 or may include a feature to retain (or lock) the brakelever 80 and prevent its rotation (along arrow A) when the brake lever80 is engaged with this feature. Any type of feature may be used toretain the brake lever 80 in the handle 22. In some embodiments, thebody of the handle 22 may include an opening to retain a distal end ofthe brake lever 80 and prevent its rotation. In some embodiments, thehandle 22 may include a first opening 22 c at the first position and asecond opening 22 d at the second position to retain the brake lever 80at these two positions. Pulling the brake lever 80 in the direction ofarrow B may pull the distal end of the lever 80 out of the first opening22 c and allow the lever 22 to rotate towards the second position in thedirection of arrow A. At the second position, the distal end of thebrake lever 80 may enter, and thereby be retained by, the second opening22 d. In some embodiments, the handle 22 may include only one opening ateither the first position or second position to lock the brake lever 80at that position. Although openings in the handle 22 are described asthe brake lever retention features, this is only exemplary. Any type offeature (such as, for example, a projection in the handle 22) may beused as a retention feature. The spring which biases the brake lever 80towards the handle 22 may be internal or external. The engagement of thebrake lever 80 with features (such as, the first and second openings 22c, 22 d) in the handle 22 serves as in integral safety interlock thatprevents inadvertent activation or deactivation of the brake mechanism70.

The brake lever 80 may be coupled through arms 82 to a cam 84 positionedwithin the handle 22. The cam 84 may include a lobe 86 shaped to pushthe shoe 72 towards the pinions 74 a, 74 b, and thereby cause the gearsof the shoe 72 to engage with the gears of the pinions 74 a, 74 b, whenthe brake lever 80 rotates from the first position to the secondposition. Releasing the lever 80 at the second position may force thedistal end of the spring loaded brake lever 80 into the second opening22 d and thereby prevent accidental rotation of the lever 80 towards thefirst position. Activation (and, in some embodiments, deactivation) ofthe brake mechanism 70 requires two deliberate movements of the brakelever 80 (pulling the brake lever 80 in the direction of arrow B, androtating the brake lever 80 in the direction of arrow A) to preventinadvertent activation of the brake mechanism 70.

In some embodiments, a compliant leaf spring 78 may be provided betweenthe cam 84 and the shoe 72 to limit the need for tight tolerance betweenthe components of the brake mechanism 70. Deformation of the leaf spring78 accommodates variations in dimensions of different parts of the brakemechanism 70, and limits the force needed to engage the brake mechanism70. In some embodiments, brake brackets 92 (see FIGS. 6A, 6B) may beprovided between the pinions 74 a, 74 b and the body of the handle 22 toallow for easy rotation of the spools 52 a, 52 b. FIG. 7B illustrates anexemplary brake bracket 92 that may be used in the brake mechanism 70.The brake bracket 92 may include an integral bearing 96 to providelubricity and alignment of the spools 52 a, 52 b with the pinions 74 a,74 b. The brake bracket 92 may also provide torsional rigidity to thebrake mechanism 70. It should be noted that the structure of the brakemechanism components described herein is only exemplary, and severalmodifications may be made to these components. For example, in someembodiments, a pinion may be incorporated with a corresponding spool(that is, the first spool 52 a may be integral with the first pinion 74a, and the second spool 52 b may be integral with the second pinion 74b), and the leaf spring 78 may be incorporated with the shoe 72.

In the embodiment of brake mechanism 70 described above, the shoe 72engages with both the first pinion 74 a and the second pinion 74 b whenthe brake mechanism 70 is activated (i.e., by moving brake lever 80 toopening 22 d). However, this is only exemplary. In some embodiments, theshoe 72 may engage with only one of the pinions during activation of thebrake mechanism 70. In such embodiments, activation of a first brakemechanism 70 may lock the movement of the guide tube 24 in one direction(for example, up-down), and activation of a second brake mechanism maylock the movement of the guide tube 24 in another direction (forexample, left-right). It is also contemplated that, in some embodiments,the shoe 72 may engage with the two pinions in stages. For example, theshoe 72 may first engage with the first pinion 74 a when the brake lever80 is rotated to the second position, and then engage with the secondpinion 74 b when the lever 80 is further rotated to a third position.Although the shoe 72 and the pinions 74 a, 74 b are described asincluding gears, this is only exemplary. In some embodiments, the gearsmay be replaced with other features (such as a pad of material with arelatively high coefficient of friction) that prevents or minimizesrelative movement between the shoe and a pinion. It is contemplatedthat, in some embodiments, brake 70 may alternatively include a strap orcable or other tensioning device configured to surround and spools 52 aand 52 b and resist or prohibit rotation of the spools when tightened.For example, a strap or cable may be formed from relatively highfriction material and tightened against portions of hubs 52 a and 52 bupon actuation of the brake lever 80. It is also contemplated that someembodiments shoe 72 and pinions 74 a and 74 b may comprise materials ofrelatively high friction or may elastically deform to improve braking.It is contemplated that any number of control wheels 50 a and 50 b aswell as any number of hubs 52 a and 52 b may be included. For example,control wheels may be stacked one on another on a single side of thehandle 22 or positioned one on each side of handle 22. In addition, itis contemplated that multiple sets of stacked control wheels may bepositioned on a single side of handle 22. In some embodiments, thestacked control wheels could control different deflection of a singlearticulation point. In other embodiments one set of control wheels couldcontrol a first articulation point and a second set of control wheelscould control a second articulation point. In such embodiments, it iscontemplated that a single brake lever could control all sets of stackedcontrol wheels or multiple brake levers could be implemented toindependently control sets of stacked control wheels. It is furthercontemplated that control wheels configured to control a singlearticulation point may be on different portions of handle 22.

FIG. 8 is a flow chart that illustrates a method of using a catheter 20including a brake mechanism 70. In the description below, reference willbe made to both FIGS. 1, 3 and 8 . The distal end 28 of the guide tube24 of the catheter 20 may be inserted into a body and pushed in untilthe distal end 28 is positioned at a work site within the body (step110). One or more surgical or therapeutic tools may be delivered to thework site through the lumens of the guide tube 24 (step 120). Dials 50 aand 50 b of the steering system 50 may be to the rotated to flex thearticulation portion 32 of the guide tube 24, and thereby suitablyposition the distal end 28 of the guide tube 24 at the work site (step130). When the distal end 28 is suitably positioned, the brake lever 80may be first disengaged from the retention feature in handle 22 (thatis, pulled out of opening 22 c) (step 140), and then rotated (in thedirection of arrow A) to engage the brake mechanism 70 (step 150).Engagement of the brake mechanism 70 locks the position of the dials 50a, 50 b, and thereby freezes the configuration of the guide tube 24(particularly the articulation portion 32) to prevent inadvertentmovement of its distal end 28. Since activation and/or deactivation ofthe locking mechanism 70 requires two deliberate movements of the brakelever 80, accidental activation or deactivation can be avoided.

The embodiments described herein are exemplary only, and it will beapparent to those skilled in the art that various modifications andvariations can be made in the disclosed systems and processes withoutdeparting from the scope of the invention. Other embodiments of theinvention will be apparent to those skilled in the art fromconsideration of the specification and practice of the inventiondisclosed herein. It is intended that the specification and examples beconsidered as exemplary only, with a true scope of the invention beingindicated by the following claims.

1-20. (canceled)
 21. A medical device, comprising: a handle having aproximal end, a distal end, and a handle body defining an interior ofthe handle; a tube extending from the distal end of the handle; anarticulation portion at a distal end of the tube; a steering systemcoupled to the handle and the articulation portion for deflection of thearticulation portion, wherein the steering system includes: a firststeering assembly including a first knob, a first shaft, a first part,and a first strand for controlling deflection of the articulationportion in a first direction, wherein the first knob is outside of thehandle body; the first shaft is coupled to the first knob and extendsfrom the first knob into the interior of the handle; the first part isfixed to the first shaft within the interior of the handle, extendsradially outward of the first shaft, and rotates with the first shaft;and rotation of the first knob about a steering axis rotates the firstshaft and the first part and pulls the first strand to deflect thearticulation portion in the first direction; and a second steeringassembly including a second knob, a second shaft, a second part, and asecond strand for controlling deflection of the articulation portion ina second direction different than the first direction, wherein thesecond knob is outside of the handle body; the second shaft is coupledto the second knob, extends from the second knob into the interior ofthe handle, and extends within and is coaxial with the first shaft; thesecond part is fixed to the second shaft within the interior of thehandle, extends radially outward of the second shaft, and rotates withthe second shaft; and rotation of the second knob about the steeringaxis rotates the second shaft and the second part and pulls the secondstrand to deflect the articulation portion in the second direction; anda brake assembly to lock the articulation portion in a deflectedconfiguration, wherein the brake assembly includes: a brake actuatorhaving an exterior portion outside of the handle body for engagement bya user, and an interior portion in the interior of the handle, and abrake in the interior of the handle and coupled to the interior portionof the brake actuator, wherein rotation of the brake actuator relativeto the handle body causes the brake to engage each of the first steeringassembly and the second steering assembly to lock the articulationportion in the deflected configuration.
 22. The medical device of claim21, wherein the rotation of the brake actuator relative to the handlebody is about a brake axis different than the steering axis.
 23. Themedical device of claim 21, wherein the engagement of the brake witheach of the first steering assembly and the second steering assemblyincludes frictional engagement.
 24. The medical device of claim 21,wherein the brake simultaneously engages a proximal side, closest to theproximal end of the handle, of each of the first steering assembly andthe second steering assembly.
 25. The medical device of claim 21,wherein the brake engages the first part of the first steering assemblyand the second part of the second steering assembly.
 26. The medicaldevice of claim 21, wherein the first shaft and the second shaft arecloser to the distal end of the handle than the exterior portion of thebrake actuator is to the distal end of the handle.
 27. The medicaldevice of claim 21, wherein the engagement of the brake with the firststeering assembly and the second steering assembly prevents rotation ofthe first knob and the second knob.
 28. The medical device of claim 21,wherein the first part includes a first spool, the second part includesa second spool, the first spool receives the first strand, and thesecond spool receives the second strand.
 29. The medical device of claim21, wherein the engagement between the brake and the first steeringassembly is closer to the first knob than the engagement between thebrake and the second steering assembly is to the first knob.
 30. Amedical device, comprising: a handle having a proximal end, a distalend, and a handle body defining an interior of the handle; a tubeextending from the distal end of the handle; an articulation portion ata distal end of the tube; a steering system coupled to the handle andthe articulation portion for deflection of the articulation portion,wherein the steering system includes: a first steering assemblyincluding a first knob, a first shaft, a first part, and a first strandfor controlling deflection of the articulation portion in a firstdirection, wherein the first knob is outside of the handle body; thefirst shaft is coupled to the first knob and extends from the first knobinto the interior of the handle; the first part is fixed to the firstshaft within the interior of the handle, extends radially outward of thefirst shaft, and rotates with the first shaft; and rotation of the firstknob about a steering axis rotates the first shaft and the first partand pulls the first strand to deflect the articulation portion in thefirst direction; and a second steering assembly including a second knob,a second shaft, a second part, and a second strand for controllingdeflection of the articulation portion in a second direction differentthan the first direction, wherein the second knob is outside of thehandle body; the second shaft is coupled to the second knob, extendsfrom the second knob into the interior of the handle, and extends withinand is coaxial with the first shaft; the second part is fixed to thesecond shaft within the interior of the handle, extends radially outwardof the second shaft, and rotates with the second shaft; and rotation ofthe second knob about the steering axis rotates the second shaft and thesecond part and pulls the second strand to deflect the articulationportion in the second direction; a brake actuator having an exteriorportion outside of the handle body for engagement by a user, and aninterior portion in the interior of the handle; and a brake in theinterior of the handle and coupled to the interior portion of the brakeactuator, wherein rotation of the brake actuator relative to the handlebody causes the brake to contact, in the interior of the handle, each ofthe first steering assembly and the second steering assembly, andwherein the contact between the brake and the first steering assembly iscloser to the first knob than the contact between the brake and thesecond steering assembly is to the first knob.
 31. The medical device ofclaim 30, wherein the rotation of the brake actuator relative to thehandle body is about a brake axis different than the steering axis. 32.The medical device of claim 30, wherein a longitudinal axis of the brakeactuator extends from the exterior portion to the interior portion andis transverse to the steering axis.
 33. The medical device of claim 30,wherein the brake simultaneously contacts a proximal side, closest tothe proximal end of the handle, of each of the first steering assemblyand the second steering assembly.
 34. The medical device of claim 30,wherein the brake contacts the first part of the first steering assemblyand the second part of the second steering assembly.
 35. The medicaldevice of claim 30, wherein the first shaft and the second shaft arecloser to the distal end of the handle than the exterior portion of thebrake actuator is to the distal end of the handle.
 36. The medicaldevice of claim 30, wherein one of the first direction and the seconddirection is up and down, the other of the first direction and thesecond direction is left and right, the first strand includes twostrands, and the second strand includes two strands.
 37. The medicaldevice of claim 30, wherein the first part includes a first spool, thesecond part includes a second spool, the first spool receives the firststrand, and the second spool receives the second strand.
 38. A medicaldevice, comprising: a handle having a proximal end, a distal end, and ahandle body defining an interior of the handle; a tube extending fromthe distal end of the handle; an articulation portion at a distal end ofthe tube; a steering system coupled to the handle and the articulationportion for deflection of the articulation portion, wherein the steeringsystem includes: a first steering assembly including a first knob, afirst shaft, a first part, and a first strand for controlling deflectionof the articulation portion in a first direction, wherein the first knobis outside of the handle body; the first shaft is coupled to the firstknob and extends from the first knob into the interior of the handle;the first part is fixed to the first shaft within the interior of thehandle, extends radially outward of the first shaft, and rotates withthe first shaft; and rotation of the first knob about a steering axisrotates the first shaft and the first part and pulls the first strand todeflect the articulation portion in the first direction; and a secondsteering assembly including a second knob, a second shaft, a secondpart, and a second strand for controlling deflection of the articulationportion in a second direction different than the first direction,wherein the second knob is outside of the handle body; the second shaftis coupled to the second knob, extends from the second knob into theinterior of the handle, and extends within and is coaxial with the firstshaft; the second part is fixed to the second shaft within the interiorof the handle, extends radially outward of the second shaft, and rotateswith the second shaft; and rotation of the second knob about thesteering axis rotates the second shaft and the second part and pulls thesecond strand to deflect the articulation portion in the seconddirection; only one brake actuator rotatable by a user to preventrotation of both of the first knob and the second knob and lock thearticulation portion in a deflected configuration, the only one brakeactuator having an exterior portion outside of the handle body forengagement by the user, and an interior portion in the interior of thehandle; and a brake in the interior of the handle and coupled to theinterior portion of the only one brake actuator, wherein rotation of theonly one brake actuator relative to the handle body causes the brake tocontact, in the interior of the handle, each of the first steeringassembly and the second steering assembly.
 39. The medical device ofclaim 38, wherein the rotation of the only one brake actuator relativeto the handle body is about a brake axis different than the steeringaxis.
 40. The medical device of claim 38, wherein a longitudinal axis ofthe only one brake actuator extends from the exterior portion to theinterior portion and is transverse to the steering axis.
 41. The medicaldevice of claim 38, wherein the brake simultaneously contacts a proximalside, closest to the proximal end of the handle, of each of the firststeering assembly and the second steering assembly.
 42. The medicaldevice of claim 38, wherein the brake contacts the first part of thefirst steering assembly and the second part of the second steeringassembly.
 43. The medical device of claim 38, wherein the contactbetween the brake and the first steering assembly is closer to the firstknob than the contact between the brake and the second steering assemblyis to the first knob.
 44. The medical device of claim 38, wherein thefirst part includes a first spool, the second part includes a secondspool, the first spool receives the first strand, and the second spoolreceives the second strand.
 45. A medical device, comprising: a handlehaving a proximal end, a distal end, and a handle body defining aninterior of the handle; a tube extending from the distal end of thehandle; an articulation portion at a distal end of the tube; a firststeering assembly including a first knob, a first shaft coupled to thefirst knob, and a first strand, wherein rotation of the first knob abouta steering axis rotates the first shaft and pulls the first strand todeflect the articulation portion in a first direction; a second steeringassembly including a second knob, a second shaft coupled to the secondknob, and a second strand, wherein rotation of the second knob about thesteering axis rotates the second shaft and pulls the second strand todeflect the articulation portion in a second direction different thanthe first direction; only one brake actuator rotatable by a user toprevent rotation of both of the first knob and the second knob, the onlyone brake actuator having an exterior portion outside of the handle bodyfor engagement by the user, and an interior portion in the interior ofthe handle; and a brake in the interior of the handle and coupled to theinterior portion of the only one brake actuator, wherein rotation of theonly one brake actuator relative to the handle body and about a brakeaxis different than the steering axis causes the brake to contact, inthe interior of the handle, each of the first steering assembly and thesecond steering assembly.
 46. The medical device of claim 45, wherein alongitudinal axis of the only one brake actuator extends from theexterior portion to the interior portion and is transverse to thesteering axis.
 47. The medical device of claim 45, wherein the brakesimultaneously contacts a proximal side, closest to the proximal end ofthe handle, of each of the first steering assembly and the secondsteering assembly.
 48. The medical device of claim 45, wherein the firstshaft and the second shaft are closer to the distal end of the handlethan the exterior portion of the brake actuator is to the distal end ofthe handle.
 49. The medical device of claim 45, wherein the contactbetween the brake and the first steering assembly is closer to the firstknob than the contact between the brake and the second steering assemblyis to the first knob.
 50. The medical device of claim 45, wherein one ofthe first direction and the second direction is up and down, and theother of the first direction and the second direction is left and right.